>I think people are taking tremendous risks eating supplements.
high doses of single minerals can reduce intake of others. but vitamin c has
no such effect as far as I know.

the problem with your anaology is that it is simply that, an anology. we
would have to look at arguments about the toxic doses of a given
vitamin/mineral.   this is somewhat overblown in the case of vitamins I
believe.  Amadeus once argued you would drop dead from vitamin A toxicity if
you walked within 50 metres of a halibut liver. my advice from someone who
actually knows [ie a scientific researcher from a Canadain university] is
that there are no known cases of vitamin A toxicity in Inuit.  and vitamin A
is the poster child of so-called hypervitaminosis.

on the other hand, deficiencies of vitamins and minerals are universal.

andrew